Aggregated particles caused by instrument artifact

Ashley M. Pierce*, S. Marcela Loría-Salazar, W. Patrick Arnott, Grant C. Edwards, Matthieu B. Miller, Mae S. Gustin

*Corresponding author for this work

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    Previous studies have indicated that superaggregates, clusters of aggregates of soot primary particles, can be formed in large-scale turbulent fires. Due to lower effective densities, higher porosity, and lower aerodynamic diameters, superaggregates may pass through inlets designed to remove particles < 2.5 μm in aerodynamic diameter (PM2.5). Ambient particulate matter samples were collected at Peavine Peak, NV, USA (2515gm) northwest of Reno, NV, USA from June to November 2014. The Teledyne Advanced Pollution Instrumentation (TAPI) 602 BetaPlus particulate monitor was used to collect PM2.5 on two filter types. During this time, aggregated particles > g2.5gμm in aerodynamic diameter were collected on 36 out of 158 sample days. On preliminary analysis, it was thought that these aggregated particles were superaggregates, depositing past PM10 (particles < g10gμm in aerodynamic diameter) pre-impactors and PM2.5 cyclones. However, further analysis revealed that these aggregated particles were dissimilar to superaggregates observed in previous studies, both in morphology and in elemental composition. To determine if the aggregated particles were superaggregates or an instrument artifact, samples were investigated for the presence of certain elements, the occurrence of fires, high relative humidity and wind speeds, as well as the use of generators on site. Samples with aggregated particles, referred to as aggregates, were analyzed using a scanning electron microscope for size and shape and energy dispersive X-ray spectroscopy was used for elemental analysis. It was determined, based on the high amounts of aluminum present in the aggregate samples, that a sampling artifact associated with the sample inlet and prolonged, high wind events was the probable reason for the observed aggregates.

    Original languageEnglish
    Pages (from-to)2225-2237
    Number of pages13
    JournalAtmospheric Measurement Techniques
    Issue number4
    Publication statusPublished - 18 Apr 2018

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    Copyright the Author(s) 2018. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


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